If the network interface is kept running during suspend, the net core
may call net_device_ops.ndo_start_xmit() while the Ethernet device is
still suspended, which may lead to a system crash.
E.g. on sh73a0/kzm9g and r8a73a4/ape6evm, the external Ethernet chip is
driven by a PM controlled clock. If the Ethernet registers are accessed
while the clock is not running, the system will crash with an imprecise
external abort.
As this is a race condition with a small time window, it is not so easy
to trigger at will. Using pm_test may increase your chances:
# echo 0 > /sys/module/printk/parameters/console_suspend
# echo platform > /sys/power/pm_test
# echo mem > /sys/power/state
To fix this, make sure the network interface is quietened during
suspend.
Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
Reviewed-by: Florian Fainelli <f.fainelli@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2aa70f8649